Process for the automatic tracking of the directional beam of a phased array antenna

ABSTRACT

A device for automatic tracking of the directional beam of a phased array antenna which includes a plurality of modules arranged in rows and columns. A part of the output voltages of the modules are coupled together to develop signals which are indicative of either the even numbered or odd numbered rows and columns of modules. The output signals are coupled to phase discriminators which develop positive or negative voltages in dependence on the sign of the angle of incidence of the arriving signal. The control voltage is then used in a closed regulating circuit to control delay lines associated with each of the modules.

United States Patent Leysieffer Aug. 8, 1972 [72] Inventor:

[73] Assignee: Siemens Aktiengesellschaft, Berlin and Munich, Germany[22] Filed: May 22, 1970 [21] Appl. No.: 39,931

Hans Leysieffer, lcking, Germany [30] Foreign Application Priority DataMay 23, 1968 Germany ..P 19 26 498.3

[52] US. Cl... .343/l17 A, 343/100 SA, 343/100 TD [51] Int. Cl. ..H0lq3/26 [58] Field of Search ..343/l17 A, 100 TD, 100 SA [5 6] ReferencesCited UNITED STATES PATENTS 3,394,374 7/1968 Weiss ..343/l00 TD Sichaket al.....343/l 17 A UX Goodwin at al.....343/l00 SA PrimaryExaminer-Benjamin A. Borchelt Assistant ExaminerRichard E. BergerAttorney-Hill, Sherman, Meroni, Gross & Simpson [57] ABSTRACT A devicefor automatic tracking of the directional beam of a phased array antennawhich includes a plurality of modules arranged in rows and columns. Apart of the output voltages of the modules are coupled together todevelop signals which are indicative of either the even numbered or oddnumbered rows and columns of modules. The output signals are coupled tophase discriminators which develop positive or negative voltages independence on the sign of the angle of incidence of the arriving signal.The control voltage is then used in a closed regulating circuit tocontrol delay lines associated with each of the modules.

6 Claims, 1 Drawing Figure PATENTEDAUS 81912 A INVENTOR flaws lays/5, 6%fi w at Z #AATTYS.

PROCESS FOR THE AUTOMATIC TRACKING OF THE DIRECTIONAL BEAM OF A PHASE!)ARRAY ANTENNA BACKGROUND OF THE INVENTION Field of the Invention Thefield of art to which this invention pertains is tracking antennas andin particular to devices for the automatic tracking of the directionalbeam of a phased array antenna.

SUMMARY OF THE INVENTION It is an important feature of the presentinvention to provide an improved device for the tracking of thedirectional beam of a phased array antenna.

It is a principal object of the present invention to provide an array ofmodules arranged in rows and columns for the purpose of tracking adirectional beam.

It is another object of the present invention to provide an array ofmodules as described above having signal outputs representative of evennumbered and odd numbered rows and columns and having such outputscoupled to phase discriminators to develop control voltages in responseto the phase difference between the odd numbered and even numbered rowsor columns.

It is an additional object of the present invention to provide an arrayas described above wherein the output of the phase discriminatorsdevelop control voltages which are used to control delay linesassociated with each of the respective modules.

BRIEF DESCRIPTION OF THE DRAWINGS The single sheet of drawings of thepresent application shows an array of modules arranged in rows andcolumns according to the present invention. The modules have beendivided into an upper array and a lower array which in actual practiceconstitute a single set of modules.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention relates to adevice for automatically tracking the directional beam of a phased arrayantenna which includes a plurality of modules arranged in a plane inrows and columns. The signal outputs are coupled together in the circuitof a receiving antenna.

Directional antennas with accessory devices for automatically tracking adirectional beam of a moving radiation source are known. Many of theknown devices are also useable with phased array antennas in which casea computer functions as an extensive intermediate member operatingusually on a digital basis. The computer delivers the necessary commandsfor the signal delays which differ in each case for the individualelements. In many uses, for example, in radio communication betweensatelites and airplanes or ships or in the case of on-board apparatusfor radar techniques, however, both the expense and the weight wouldbecome too great. Because of the expense and other technologicalreasons, mechanically rotatable tracking antennas are not useable.Therefore, there exists the need to develop a simple phased arrayantenna having an automatic directional beam tracking system that can beoperated without the use of computers.

According to the invention this is achieved in a simple manner. A partof the output voltages of the modules, decoupled from the useful signalsupplied to the receiver, are coupled together in such a way that thesignals are indicative of either the even numbered modules or the oddnumbered modules in the respective rows and columns. Thus there are twooutputs for the rows and two outputs for the columns. These outputs aresupplied to the inputs of two phase discriminatOIS.

From each of the phase discriminators there is delivered a positive ornegative direct voltage in dependence on the sign of the angle ofincidence of the arriving signal. The direct voltage is used as acontrol voltage for the delay lines of the associated modules so that aclosed regulating circuit results which is in equilibrium when theoutput signals of all the individual modules are in phase. Depending onthe spatial position of a received wave front the output signals areadded vectorially. Through the displacement of the groups in each caseby the module spacing in the direction of the columns as well as also inthe direction of the rows, however, the phase of the sum signal suppliedin each case to a phase discriminator is dependent on the angles ofinclination in the direction of the rows and the direction of thecolumns between the array plane and the wave front plane. A prerequisitefor the faultless functioning of the phased array antenna is, in thisconnection, the reciprocal decoupling of all the emitter elements.

Referring to the drawing, there is used a surface antenna with 6 X6elements in which the columns and rows are arranged perpendicular to oneanother in X and Y directions. Each module of the phased array antennahas a delay line L in the radio frequency or intermediate frequencyplane. In the latter case, the intermediate frequency is formed byconversion with a common converter generator within each in-phase feed.The transit time of the delay members L is varied with a direct voltagesubstantially proportionally to this.

The modules, in the interest of clarity, are represented twice, namelyin an upper and in a lower array configuration. The upper array receivessymbollically the controllable delay lines L, and the lower the othermodule components M with, in each case, two signal outputs. These twosignal outputs are coupled together at an output A at which the antennasignal for the receiver is taken.

In the actual installation the constituents which are represented aboveand below in the drawing are components of one and the same module. Inthe lower part of the drawing, the outputs which are coupled together inthe X direction are designated with X. The outputs coupled together inthe Y direction are designated Y. In both directions the correspondingoutputs of the even numbered rows and columns (X X X and Y Y Yrespectively) and odd numbered rows and columns (X X,, X and Y Y Yrespectively) are grouped together. The signals of the two X groups aresupplied to a phase discriminator P1 of the X direction and those of thetwo Y groups to a similar discriminator P2 of the Y direction. Theinputs to the phase discriminators P1 and P2 are decoupled by thedecoupling resistors E from the output A. The direct voltages deliveredfrom the discriminators P1 and P2 are amplified in two amplifiers V1 forthe X direction and V2 for the Y direction and coupled to two switches Son the control inputs of the delay lines L.

The control voltages delivered from the amplifiers V1 and V2 are dividedin a voltage divider consisting of like resistors R. For both directionsin each case a tap couples a row of control inputs. The voltagedelivered in each case for the X direction and Y direction to a moduleis added and supplied in common to the respective delay lines L ascontrol voltages.

Through the use of the voltage divider and the fact that therelationship between control voltage and group transit time of the delaylines L, equal among them selves, is very nearly linear, it is achievedthat there is obtained a radiation diagram with approximately optimalconcentration independently of the two control voltages. The magnitudeof the X and Y control voltage determines only the direction of the beambundle in respect to the array plane.

A signal incident perpendicularly upon the array plane delivers a signalvoltage in the same phase on all the module outputs. The two phasediscriminators P1 and P2 deliver no voltages, and the regulating circuitis in equilibrium. Now if the wave front changes its direction, then thevoltages of the modules in each case no longer add linearly, butvectorially. Between the sum voltages of the two lines conducted to adiscriminator P1 or P2 there exists then through the group displacement,depending on the angular deviation of the wave front in the X and Ydirections, a phase difference which brings about a correspondingcontrol voltage on the phase discriminator outputs. With correctconnection of the amplifiers V1 and V2 there is yielded a variation ofthe transit time in the delay lines L in such a way that again thevoltages of all the outputs are added very nearly linearly. Thedirectional beam is thus tracked. The loop amplification of theregulating circuit is chosen, for the achievement of a stable behavior,of such a magnitude that for maximum deflection of the directional beam,for example 60 in X and Y directions, output voltages of the phasediscriminators P1 and P2 are developed by phase differences of a fewdegrees, for example 3.

If at first no signal comes in, the switches S connect the two controllines with a generator SG. The generator SG delivers alternatingvoltages of differing frequencies. If in the course of a searching phasea signal of sufficient intensity appears on the output, the switches Sare thrown with sufficient rapidity by a switching arrangement B so asto initiate the tracking process.

With decreasing band width of the feed channels to the discriminators,the sensitivity of the tracking to noise and similar interferencesbecomes less. The band width of the feed channels is expediently adaptedto the spectral quality of the received signal.

Phased array antennas can be used for transmitting as well as receiving.The modules then each have a transmitting and a receiving branch, which,in the case of equal transmitting and receiving frequency are connectedin alternation or in the case of difiering transmitting and receivingfrequencies, are connected over frequency branching networks to theradiator element. In this context, various types of switching of thecontrollable delay lines are possible.

Separate transmitting and receiving antennas can be used each with a setof delay lines either in the RF or the ZF plane. There the controlvoltages for the delay lines of the receiver array antenna are likewisefed to the corresponding delay lines of the transmitter array antenna.With like transmitting and receiving frequency and alternating operationof transmitter and receiver, however, the control voltage valve yieldedin the receiption has to be stored for the purpose of lattertransmitting in the receiving direction. If a common phased arrayantenna is used for the receiving and transmitting, then, for example,in the ZF parts of the transmitter, there can be accommodated a set ofdelay lines or also a common set of delay lines in the microwave plane.

There are also arrangements with a converter system which contains acommon intermediate frequency part for both transmitting and receivingand which also contains a common delay line. In all these cases it ispossible according to this invention, with use of like transmitting andreceiving frequencies, to transmit with corresponding trackeddirectional antennas, if the tracking control voltages of the variousdirections present are stored until transmission and are placed duringtransmission on the voltage divider. In the executed example, thestorage take place in a storer C, from which the stored control voltagesfor the specific direction are colled off according to a transmittingcommand given from a control input D over the switch 8.

I claim as my invention:

1. Apparatus for automatically tracking the directional beam of a phasedarray antenna comprising: a plurality of receiving modules, said modulesbeing arranged in rows and columns, a delay line associated with eachmodule, phase discriminator means for developing a control voltage inresponse to the phase of a received signal, means for using said controlvoltage to vary the delay of the delay lines associated with eachmodule, the outputs of each of said modules in respective rows andcolumns being coupled together, the outputs of odd numbered rows andcolumns being coupled to respective inputs of the phase discriminatormeans, outputs of even numbered rows and columns being coupled to otherrespective inputs of said phase discriminator means whereby two inputsare provided for the columns of the array, said phase discriminatormeans including first and second phase discriminators for developingpositive and negative direct voltage outputs in dependence on the signof the angle of incidence of the received signal, first and secondvoltage dividers, said phase discriminators having outputs which arecoupled to said first and second respective voltage dividers, said firstvoltage divider having a series of taps each of which is connected to arespective common input of the delay line of a given row, said secondvoltage divider having a series of taps each of which is connected to arespective common input of the delay lines of a given column.

2. Apparatus for automatically tracking the directional beam of a phasedarray antenna in accordance with claim 1 wherein the respective delaylines comprise a closed loop regulating circuit.

3. Apparatus for automatically tracking the directional beam of a phasedarray antenna in accordance with claim 1 wherein during the transit from5. Apparatus for automatically tracking the directional beam of a phasedarray antenna in accordance with claim 1 wherein the rows and columnsare arranged perpendicularly to each other in an X and Ylattice.

6. Apparatus for automatically tracking the directional beam of a phasedarray antenna in accordance with claim 5 wherein the spacing between themodules is in the order of one-half wavelength of the signal to bereceived.

1. Apparatus for automatically tracking the directional beam of a phasedarray antenna comprising: a plurality of receiving modules, said modulesbeing arranged in rows and columns, a delay line associated with eachmodule, phase discriminator means for developing a control voltage inresponse to the phase of a received signal, means for using said controlvoltage to vary the delay of the delay lines associated with eachmodule, the outputs of each of said modules in respective rows andcolumns being coupled together, the outputs of odd numbered rows andcolumns being coupled to respective inputs of the phase discriminatormeans, outputs of even numbered rows and columns being coupled to otherrespective inputs of said phase discriminator means whereby two inputsare provided for the columns of the array, said phase discriminatormeans including first and second phase discriminators for developingpositive and negative direct voltage outputs in dependence on the signof the angle of incidence of the received signal, first and secondvoltage dividers, said phase discriminators having outputs which arecoupled to said first and second respective voltage dividers, said firstvoltage divider having a series of taps each of which is connected to arespective common input of the delay line of a given row, said secondvoltage divider having a series of taps each of which is connected to arespective common input of the delay lines of a given column. 2.Apparatus for automatically tracking the directional beam of a phasedarray antenna in accordance with claim 1 wherein the respective delaylines comprise a closed loop regulating circuit.
 3. Apparatus forautomatically tracking the directional beam of a phased array antenna inaccordance with claim 1 wherein during the transit from reception totransmission storage means are provided to store the control voltage forthe delay line for use during a subsequent transmitting process. 4.Apparatus for automatically tracking the directional beam of a phasedarray antenna in accordance with claim 1 wherein an AC voltage generatoris employed and switching means are provided to couple said voltagegenerator to the delay lines in the absence of a receiving signal, andwherein means are provided to switch out the voltage generator andswitch in the regulating means when a signal exceeding a threshold levelis received.
 5. Apparatus for automatically tracking the directionalbeam of a phased array antenna in accordance with claim 1 wherein therows and columns are arranged perpendicularly to each other in an X andY lattice.
 6. Apparatus for automatically tracking the directional beamof a phased array antenna in accordance with claim 5 wherein the spacingbetween the modules is in the order of one-half wavelength of the signalto be received.